Machine tools abstract
A transfer for machine tools, in particular presses, including
a pair of parallel bars supporting the elements to be transferred
and borne longitudinally sliding on supports. The supports are movable
in a crosswise direction to the bars, to vary the distance between
them, and in a direction at right angles to the plane containing
the pairs of bars. The bars are made to move longitudinally by motors
interposed between each bar and the corresponding support.
Machine tools claims
What is claimed is:
1. Transfer for machine tools, in particular presses, comprising
a pair of parallel bars for supporting elements to be transferred
and further comprising supports for the bars, the supports being
movable in a crosswise direction to the bars to vary the distance
between them and in a direction at right angles to the plane containing
the pairs of bars, and linear motors interposed between each bar
and the corresponding support to move the bars longitudinally.
2. Transfer as claimed in claim 1 wherein two reciprocally movable
parts of the linear motor are secured directly to the bar and to
the support respectively.
3. Transfer as claimed in claim 2 wherein the linear motor is
received between linear guides for interconnection between the bar
and the support.
4. Transfer as claimed in claim 1 wherein the support is guided
to move in a direction perpendicular to the plane containing the
bars, and a saddle on a bedplate is guided to move the bars in a
crosswise direction to the bars.
5. Transfer as claimed in claim 4 wherein the movement of the
support with respect to the bedplate is controlled by a linear motor.
Machine tools description
BACKGROUND OF THE INVENTION
Field of the Invention
This invention refers to transfer presses, and more in particular
to the transfer mechanism associated with them. Transfers for presses
are generally composed of a pair of parallel bars, onto which the
elements for gripping the pieces to be transported are designed
to be fitted. These elements can have the most diverse configurations,
in relation to the processing to be carried out and the configurations
of the pieces.
In these transfers, the pair of bars is guided in a longitudinal
forward movement and must also be movable in a vertical direction.
Moreover, the two bars must be provided with reciprocal movements
to bring them close to and away from each other.
Hence, each bar is movable along three orthogonal axes.
More in particular, according to the commonly used conventional
transfer structure, the bars are carried on supports which are made
to move vertically, by means of a motorized control, on saddles
capable of sliding horizontally, crosswise to the bars. The two
saddles are made to move away from or close to each other by suitable
motors, to define the distance between the bars. The bars are also
movable longitudinally on the supports.
According to the known technique, the mechanism for the longitudinal
movement of the bars comprises a stationary drive unit of various
type, which draws the bars in their longitudinal movement through
a kinematic coupling which engages the bars longitudinally only,
allowing them to maintain their vertical and transversal freedom
This unit acts on the ends of the bars and causes a considerable
obstruction in correspondence with the head of the transfer. Moreover,
it is complicated and expensive to control the bars by means of
a connection which leaves the bars two degrees of freedom of movement
along the axes perpendicular to the longitudinal axis.
SUMMARY OF THE INVENTION
To obviate these problems, according to the invention a transfer
for machine tools, in particular presses, comprises a pair of parallel
bars for supporting the elements to be transferred and carried longitudinally
sliding on supports, the supports being movable in a crosswise direction
to the bars in order to vary the distance between them and in a
direction perpendicular to the plane containing the pairs of bars,
and is characterized by the fact that the bars are made to move
longitudinally by motors interposed between each bar and the corresponding
BRIEF DESCRIPTION OF THE DRAWINGS
The technical solution identified by the invention will be more
clearly evident from the following description of an exemplificative
embodiment, schematically illustrated in the accompanying drawings,
FIGS. 1 and 2 respectively show a plan view and a front elevational
view of a transfer according to the invention.
FIG. 3 shows an enlarged view of a section along the line III--III
represented in FIG. 1.
FIG. 3A shows an enlarged view of an area encircled in FIG. 3.
DETAILED DESCRIPTION OF THE INVENTION
The transfer is composed of two bedplates 10 equally spaced apart.
Mounted on each bedplate are two saddles 11 movable on linear
bearings 12. Mounted on each saddle is an actuating element 13 which
vertically moves a support 14 which is consequently provided with
a horizontal and vertical movement. Carried on each support, by
means of linear roller bearings 15 is a bar 16. Secured respectively
to the bar 16 and to the support 14 are the two reciprocally movable
parts 18 19 of a linear electric motor generically indicated by
reference 17. A linear motor 20 wholly similar to the motor 17
is interposed between each movable saddle 11 and the bedplate 10
to control the linear movement of the saddle in a crosswise direction
to the bars 16.
For the movement of each support 14 in a vertical direction and
in a horizontal direction perpendicular to the bars, actuators 13
and 20 respectively have been exemplified. However, these servomotor
members for carrying out these movements, with their respective
kinematic control mechanisms, can in any case be made according
to the techniques traditionally used in these transfers, for the
same purpose. An essential characteristic of the transfer according
to the invention is to use the linear motor 17 interposed between
supports 14 and bars 16 to effect the longitudinal stroke of the
bar, thereby avoiding the conventional use of a pulling device acting
on one of the ends of the bars by means of a connection which leaves
the bars free to move vertically and towards each other.
According to the invention, the linear servomotor 17 for control
of the longitudinal translation of the bars operates directly between
the bar and the support that slidingly carries it, the movements
according to the other two axes being carried out by the supports.
The actuator 13 can also be composed of a linear motor, like the
servomotors 17 and 20 even though other known controls can be equivalently
used, if necessary mechanically connected to the device that raises
the other support fitted in correspondence with the same bedplate,
for the coordinated movement of the two bars.
The linear motors can be chosen from among any suitable type capable
of making the controlled elements go through those step-by-step
movements typical of the type of transfer that the invention refers
to. In the described embodiment, the linear motor is received between
the guides for the longitudinal sliding of the bars. However, the
motor may be disposed in any other suitable position between the
support and the bar. For example, the supports 14 may have bases
secured to them which are shaped in such a way as to receive one
of the elements of the motor, the other element of the motor being
secured directly to the bar or to a suitable base secured to the